Surgical management
Careful attention to metabolic status and nutritional
management is necessary before, during, and after
surgical procedures. In addition to higher energy needs
as a result of surgery (Long et al 1979), patients are at
risk for inadequate energy intake because of the
necessity for fasting prior to surgery. Patients may also
be told to stop taking all medications while fasting.
The metabolic dietitian and physician should work
with the surgeons to ensure that there is no risk of
decompensation prior to or during the surgery by
admitting the patient to the hospital before planned
surgery and providing them with intravenous glucose
and lipid emulsion, as necessary. The surgical team
must be reminded to give the patient a dose of
N-scavenging drug before surgery, and to double the
first dose after surgery, if necessary. If the surgical
procedure is lengthy, total parenteral nutrition to
provide energy and fluids should be continued during
the operation and post surgery. Patients should be
given enteral nutrition as soon as the gastrointestinal
tract regains function. Unpublished work shows that
the gastrointestinal tract has regained some function
by 6 hours post surgery, and partial feeding may be
started then. This careful attention and teamwork is
essential in preventing a rebound in plasma ammonia
concentration during or after surgery.
Clinical experience in patients with a UCD receiving
a liver transplant confirms the need for close
monitoring prior to, during, and following surgery.
Before surgery, the patient may be transfused, and
albumin replacement is given. Elevated plasma ammonia
concentrations may develop quickly, requiring the
removal of all dietary protein combined with administration
of protein-free energy sources. Hyperalimentation,
including dextrose and intravenous L-arginine
along with intravenous sodium benzoate and sodium
phenylacetate (Ammonul), is used during the transplantation
procedure. Two days of sodium phenylbutyrate
(Buphenyl) and a low protein intake may be
required to normalize plasma ammonia concentrations
post-transplantation.